Volume of Spheres (((Find the volume of each sphere. Round to the nearest tenth.)))

The last one is (( 6.7ft ))

Please show your work
I will give brainliest ♡︎

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Please someone help

Dylan and dusty plan to take weekly surfing lessons together. if the 2-hour lessons are $20 per person and they plan to spend $100 each on new surfboards, what is the maximum number of lessons the two can take if the total amount spent for lessons and surfboards is at most $480?

What is the volume of a cone with a height of 6 cm in the radius of 2 cm

Abicycle training wheel has a radius of 3 inches. the bicycle wheel has a radius of 10 inches. approximately how much smaller, in square inches and rounded to the nearest hundredth, is the area of the training wheel than the area of the regular wheel? *